scholarly journals Respiratory quotients during embryogenesis of Rana pipiens

1953 ◽  
Vol 18 (18) ◽  
pp. 61
Author(s):  
Erasmo G. Mendes
Keyword(s):  
Rana Pipiens

Fizeram-se experiências com diferentes estádios embrionários de Rana pipiens a fim de determinarem os quocientes respiratórios (QR) de cada estádio ou pequeno grupo de sucessivos estádios. A finalidade principal da pesquisa foi verificar se a rã comum da Nova Inglaterra (Estados Unidos) mostra a mesma flutuação de valores do QR durante o desenvolvimento embrionário que a rã europea, R. fusca, de acôrdo com o trabalho de Brachet (1934). Segundo êsse autor, o QR do ovo não fecundado é aproximadamente 1.0 e, como consequência da fecundação, baiza a um valor indicativo de metabolismo preponderantemente lipídico, até o início da gastrulação, quando retorna à unidade, para aí permanecer mais ou menos até a fase de vida livre.

Comparative Morphology of Intercellular Bridges Between Developing Germ Cells of the Ovary

1970 ◽  
Vol 28 ◽  
pp. 328-329
Author(s):  
J. R. Ruby ◽  
R. F. Dyer ◽  
R. G. Skalko ◽  
R. F. Gasser ◽  
E. P. Volpe
Keyword(s):  
Germ Cells ◽  
Rana Pipiens ◽  
Comparative Morphology ◽  
Dense Material ◽  
Individual Species ◽  
Microscope Examination ◽  
Electron Dense Material ◽  
Intercellular Bridges ◽  
Cytoplasmic Side ◽  
Intercellular Connections

An electron microscope examination of fetal ovaries has revealed that developing germ cells are connected by intercellular bridges. In this investigation several species have been studied including human, mouse, chicken, and tadpole (Rana pipiens). These studies demonstrate that intercellular connections are similar in morphology regardless of the species.Basically, all bridges are characterized by a band of electron-dense material on the cytoplasmic side of the tri-laminar membrane surrounding the connection (Fig.l). This membrane is continuous with the plasma membrane of the conjoined cells. The dense material, however, never extends beyond the limits of the bridge. Variations in the configuration of intercellular connections were noted in all ovaries studied. However, the bridges in each individual species usually exhibits one structural characteristic seldom found in the others. For example, bridges in the human ovary very often have large blebs projecting from the lateral borders whereas the sides of the connections in the mouse gonad merely demonstrate a slight convexity.

The application of video-enhanced constrast/differential interference constrast microscopy in conjunction with whole mount electron microscopy to the study of organelle transport

1988 ◽  
Vol 46 ◽  
pp. 66-67
Author(s):  
J. H. Hayden
Keyword(s):  
Electron Microscopy ◽  
Rana Pipiens ◽  
Silver Film ◽  
Immunofluorescence Microscopy ◽  
Organelle Transport ◽  
Linear Element ◽  
Whole Mount ◽  
Carbon Coated ◽  
Linear Elements ◽  
Dic Microscopy

In a previous study, Allen video-enhanced constrast/differential interference constrast (AVEC-DIC) microscopy was used in conjunction with immunofluorescence microscopy to demonstrate that organelles and vesicle move in either direction along linear elements composed of microtubules. However, this study was limited in that the number of microtubules making up a linear element could not be determined. To overcome this limitation, we have used AVEC-DIC microscopy in conjunction with whole mount electron microscopy.Keratocytes from Rana pipiens were grown on glass coverslips as described elsewhere. Gold London Finder grids were Formvar- and carbon coated, and sterilized by exposure to ultraviolet light. It is important to select a Formvar film that gives a grey reflection when it is floated on water. A silver film is too thick and will detract from the image in the light microscope.

scholarly journals NUTRITIONAL STUDIES ON THE GROWTH OF FROG LARVÆ (RANA PIPIENS)

1919 ◽  
Vol 38 (2) ◽  
pp. 325-344
Author(s):  
A.D. Emmett ◽  
Floyd P. Allen ◽  
G.O. Luros ◽  
M. Sturtevant
Keyword(s):  
Rana Pipiens ◽  
Nutritional Studies

Self-Inhibition of Growth in Rana pipiens Tadpoles

1966 ◽  
Vol 39 (4) ◽  
pp. 341-356 ◽  
Author(s):  
Gwynn Collins Akin
Keyword(s):  
Rana Pipiens ◽  
Inhibition Of Growth

Capillary permeability: atrial peptide action is independent of "protein effect"

1990 ◽  
Vol 259 (5) ◽  
pp. H1351-H1356 ◽  
Author(s):  
V. H. Huxley ◽  
D. J. Meyer
Keyword(s):  
Hydraulic Conductivity ◽  
Bovine Serum Albumin ◽  
Atrial Natriuretic Peptide ◽  
Rana Pipiens ◽  
Capillary Permeability ◽  
Barrier Properties ◽  
Effective Area ◽  
Small Rise ◽  
Mesenteric Microvessels ◽  
Exchange Vessel

Perfusion of exchange microvessels with the vasoactive hormone, atrial natriuretic peptide (AP), acutely and reversibly elevates hydraulic conductivity (Lp) by mechanisms that are, as yet, unknown. This, the first of two studies to characterize AP responses when perfusate composition was altered, specifically focuses on the action of AP when perfusate albumin was lowered to change the transcapillary barrier properties for water by passive mechanisms (protein effect). Perfusion of frog (Rana pipiens) mesenteric microvessels with 1 nM AP in 10 mg/ml bovine serum albumin (BSA) elevated Lp by a median 2.1-fold (range 1.2-2.7, n = 13) from control levels (10 mg/ml BSA). Reduction of perfusate albumin from 10 to 1 mg/ml elicited a small rise in Lp (1.8-fold, n = 10); Lp rose a further 2.1-fold (n = 6) when 1 nM AP was added to 1 mg/ml BSA. Likewise, protein-free perfusion elevated Lp from a median 2.2 to 5.1 X 10(-7) cm.s-1.cmH2O-1 (n = 11); 1 nM AP in protein-free perfusate elevated Lp a further 2.1-fold (n = 8). Thus, regardless of protein content, the response to the peptide was a consistent, twofold increase in exchange vessel Lp (n = 27). These data are consistent with the suggestion that the AP-activated rise in Lp (twofold) occurs via an increase in the effective area of the transcapillary pathway for water without influencing the selectivity properties of the paracellular, albumin-sensitive portion of the barrier.

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